unraisablehook enhancements

[graingert]

Could help with #10404

[graingert]

# test_demo.py
import asyncio
import pytest

async def my_task():
    pass

def test_scheduler_must_be_created_within_running_loop() -> None:
    with pytest.raises(RuntimeError) as _:
        asyncio.create_task(my_task())

This is an improvement it works now if you do: python -W error -m pytest test_demo.py because there's an issue where warnings filters are removed too early

[graingert]

These fixes probably need to be applied to the thread hooks